Prius hybrid to get rooftop solar panel

Motor mammoth Toyota, maker of the famed Prius hybrid car, is rumoured to be thinking about fitting some new Prius models with solar panels. The possible move is unlikely to seriously affect the car's fuel consumption, however, and is being seen by some as a PR stunt.

Toyota is offering no official comment on the suggestions, which were first reported in Japanese business daily Nikkei. However, Reuters quotes an anonymous source "briefed on the matter" as saying that the plans were "a symbolic gesture" which would do little more than provide part of the power used by the Prius' air conditioning.

"It's very difficult to power much more than that with solar energy," added the informant.

This view certainly squares with the well-understood performance of solar panels, especially small ones which can be fitted onto a car roof (as the Prius ones will reportedly be). Such panels can already be bought as accessories, and one was also included in the recent "Provoq" concept fuel-cell hybrid design from GM. In neither case can large amounts of power - suited to actually propelling a car, rather than running ancillary electronics - be harvested in a reasonably short time. You'd have to leave your car parked in the sun for ages to charge up even a normal car battery, let alone one which could actually drive the car usefully. (Which the Prius' can't, by the way. Toyota has thus far turned its face resolutely away from cars which can store enough electricity to make journeys solely on battery power.)

Panels of this kind are still useful, however, as they can prevent a car's battery running flat while parked due to the constant trickle of power used by security systems and so forth. With a heftier hybrid battery, you might also be able to run the air-con for a bit longer while stationary before the engine had to fire up. This is probably all that Toyota actually intends to offer.

However, the Prius remains the only car being driven globally which is actually different from normal internal combustion jobs in its power-train engineering. Thus it attracts a great deal of eco-hype and attention, and the addition of a solar panel - even though it won't offer a lot more benefit than a twenty quid job from Maplins slipped into your sunroof shutter - will perhaps be seen as justifying a substantially bigger markup on the car price. ®